This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Sir2 (Silent Information Regulator-2) proteins link aging and lifespan regulation, genomic stability, and metabolism in multiple model organisms. Recent work indicates that mammalian Sir2 protein SIRT6 suppresses genomic instability and attenuates the onset of several age-associated pathologies. SIRT7, a closely related protein, has also been linked to aging in some mouse studies. However, much remains to be learned about the molecular mechanisms of SIRT6 and SIRT7 function. Our work focuses on a systematic characterization of the basic molecular mechanisms through which SIRT6 and SIRT7 function, using a combination of biochemistry and cell biology in human cells, genomic and proteomic analyses, and complementary studies of the SIRT6 and SIRT7 homologs in drosophila flies. This work will be instrumental for elucidating fundamental biological processes that impact on human health and aging, cancer, and metabolism. A series of biochemical, cellular, and global proteomic and genomic analyses are being carried out to define the molecular functions of SIRT6 and SIRT7 in mammalian and drosophila cells. We propose: 1. To elucidate novel mammalian SIRT6 and SIRT7 regulated molecular pathways. Proteomic and biochemical approaches are taken to isolate and identify SIRT6 substrates, protein binding partners, and macromolecular complexes. 2. To elucidate novel molecular pathways regulated by drosophila dSIRT6 and dSIRT7. Proteomic and biochemical approaches are taken to isolate and identify their substrates, protein binding partners, and macromolecular complexes. Mass Spectrometry analysis with the UCSF Mass Spectrometry Facility will be essential for these aims.